Patients whose lumbar spinal stenosis was treated with decompression surgery plus
fusion ended up no less disabled than those who had decompression alone, but they
did lose more blood, stay hospitalized longer, and have higher medical bills, according
to two studies published in the April 14 issue of the New England Journal of Medicine.

Outcomes from these randomized controlled trials call into question the current enthusiasm
for decompression plus fusion, now routinely performed in more than half of patients
with surgically treated spinal stenosis in the United States (including 96% of those
with degenerative spondylolisthesis).

Neither research group found that adding fusion improved scores on the Oswestry Disability
Index (ODI), a disease-specific scale used to assess disability related to low back
pain at 2 and 5 years after surgery. One study found a 5.7-point difference on the
more general physical component summary score of the Medical Outcomes Study 36-Item
Short Form Health Survey (SF-36), but that difference barely cleared the 5-point
criterion for minimal clinical importance.

In an accompanying editorial, Wilco C. Peul, MD, PhD, and Wouter A. Moojen, MD, PhD,
write, "The goal of surgery in lumbar spinal stenosis is to improve walking distance
and to relieve pain by decompression of nerve roots. The addition of instrumented
fusion — 'just to be sure' — for the treatment of the most frequent forms of lumbar
spinal stenosis does not create any added value for patients and might be regarded
as an overcautious and unnecessary treatment." Dr Peul and Dr Moojen are both from
Leiden University Medical Center and Medical Center Haaglanden, The Hague, the Netherlands,
and were not involved in either of the studies.

The aim of the first study, the Swedish Spinal Stenosis Study (SSSS), reported by
Peter Försth, MD, PhD, from the Department of Surgical Science, Uppsala University,
Sweden, and colleagues, was to determine whether combining fusion surgery with decompression
surgery resulted in better clinical outcomes at 2 years than decompression surgery
alone.

The trial included 247 patients with lumbar spinal stenosis at one or two adjacent
vertebral levels who were randomly assigned either to decompression (laminectomy)
alone or to decompression plus fusion surgery. About half of the patients also had
degenerative spondylolisthesis, defined as presence of a vertebra that had slipped
at least 3 mm past the vertebra below it.

Randomization was stratified for presence or absence of degenerative spondylolisthesis.
The authors write, "Many spine surgeons view this sign of instability as a mandatory
indication for fusion surgery."

The primary outcome in the Swedish study was the score on the ODI 2 years after surgery.
The researchers also assessed patient-reported outcome measures, a 6-minute walk
test, and a health economic evaluation, as well as 5-year data where available.

The second study was the Spinal Laminectomy versus Instrumental Pedicle Screw (SLIP)
trial, reported by Zoher Ghogawala, MD, and colleagues in the United States. Dr Ghogawala
is from the Alan L. and Jacqueline B. Stuart Spine Research Center, Lahey Hospital
and Medical Center, Burlington, Massachusetts.

The SLIP researchers randomly assigned 66 patients, all of whom had symptomatic lumbar
spinal stenosis and grade 1 degenerative spondylolisthesis, either to decompressive
laminectomy alone or to laminectomy with posterolateral instrumented fusion. The
authors note that in 2011, 465,000 spinal fusion procedures were performed in the
United States, at a cost of $12.8 billion, the highest aggregate hospital costs of
any surgical procedure performed in US hospitals.

Their study tested the hypothesis that lumbar laminectomy with instrumented fusion
(rigid pedicle screws affixed to titanium alloy rods) would produce better outcomes
on the SF-36 than laminectomy alone. The primary outcome measure was change in the
SF-36 at 2 years. The SLIP trial included ODI score as a secondary outcome measure.

Neither study showed a significant difference in disability (measured by the ODI)
associated with adding fusion to decompression surgery for spinal stenosis. In the
SSSS, the mean ODI at 2 years was 27 in the fusion group and 24 in the decompression-alone
group (P = .24). In the smaller SLIP study, the change in ODI at 2 years was −26.3
in the fusion group and −17.9 in the decompression-alone group (P = .06).

Furthermore, in SSSS, adding fusion had no effect on disability score in the group
of patients expected to be most likely to benefit: those with degenerative spondylolisthesis.

Dr Peul and Dr Moojen comment that in the SSSS study, decompression with fusion "was
associated with higher costs [an additional $6800,] but did not provide improvement
with respect to the primary outcome measure, the ODI, or to any other clinical outcome,
including walking distance."

Researchers in the SLIP study report that their primary outcome, the SF-36 at 2 years
after surgery, increased by 15.2 for the fusion group vs 9.5 for the decompression-alone
group, for a difference of 5.7 (P = .046).

The SF-36 physical component summary score increases continued to be greater in the
fusion group than in the decompression-alone group at 3 and 4 years. However, the
study sample size had been calculated with the assumption that 10% of patients would
be lost to follow-up each year. By year 2, 14% of patients had been lost, and by
year 4, 30% of patients were lost to follow-up. The authors write, "The interpretation
of the differences observed at the 3-year and 4-year time points are weakened by
the lower rates of follow-up. Future studies will benefit from larger sample sizes
that also include valid disease-specific assessments as primary outcomes."

Adjunct fusion was also associated with other problems. Length of hospital stay for
fusion vs decompression alone was 4.2 vs 2.6 days in the SLIP study (P < .001) and
7.4 vs 4.1 days in the SSSS study (P < .001). In the SLIP patients, mean blood loss
was 513.7 mL for fusion vs 83.4 mL for decompression alone (P < .001).

According to Dr Peul and Dr Moojen, Dr Ghogawala and colleagues were correct to conclude
that the difference in SF-36 score does not justify the associated higher costs or
longer duration of surgery (289.6 vs 124.4 minutes).

The editorialists conclude, "Given that the disease-specific ODI is a better outcome
measure for the treatment of spinal stenosis than the general SF-36, the fact that
both trials showed that the improvements in the scores on the ODI did not differ
significantly between the two surgical approaches suggests that the costlier approach
of instrumented fusion does not add value for patients."